Doesn't work on ubuntu 2004 or am I doing something wrong.

[bigorado]

Good afternoon, I'm installing on a VPS as shown on the git page, I'm going to the web interface. It swears that port 53 is busy. There is no fix button, apparently this functionality was cut out. I do everything as stated in the troubleshooting instructions. I get:
sudo lsof -i :53
AdGuardHo 1443 root 11u IPv6 25449 0t0 UDP *:domain
AdGuardHo 1443 root 12u IPv6 25450 0t0 TCP *:domain (LISTEN)
But the server does not see clients, neither the router, nor other servers, windows. Accordingly, it does not load anything and does not work. There is no firewall or blocking on the server. Tell me where to look. Newbie in Linux.